Plate printing machine



S p 1927' R. K. CARSON PLATE PRINTING MACHINE Filed Nov. 17, 1924 IN V-EN TOR.

m 41 mod/472 M.

ATTORNEY.

Patented Sept. 6, 1927.

UNITED STATES rarest OFFICE.

ROY K. CARSON, OF DETROIT, MICHIGAN, AElSIGNQR TO WILLIAM J. CARSON, OF

DETROIT, MICHIGAN.

PLATE PRINTING MACHINE.

Application filed November 17, 1924. Serial No. 750,353.

. This invention relates to the production of half-tone plates for printing pictures and other designs, and its object is to provide means whereby high grade plates may be produced by comparativelyunskilled operators and at comparatively low cost and wherein plates may be produced with clear high-lights and well defined tone eifects.

Thisinvention comprises a support and a pair of screens movably mounted thereon so that these screens may alternately occupy a definite operative position, and plate holder adaptedto be so moved as to carry a sen; sitized plate into contact, with either oi said screeens or into contact with a negative which is in contact with one oit' said screens.

It also consists'in one of the screens being formed with heavier lines than the other so that the areas of the sensitized plate af: fected by the light passingtherethrougn will be smaller, the two plates being relatively adjustable, so that the same areas oi the sensitized plate will be ailccetd by the light passing through between the lines oi both of the screens. 7

It further consists of the details of construction illustrated in the accompanying drawing and particularly pointed out int-he claims.

In the accompanying drawing, Fig. 1 is a perspective View of'this improved printing device. Figs. 2 and 3 are'elevations of adjustable bearings adapted tor-this pr nting device. Fig. 1 is a central longitudinal. section of the holder for the sensitized plate. Similar reference characters refer to like parts throughout the several views. I

It is desirable that those areas oi halftone plates which are to print the highlights should be'provlded with fine, closely spaced points or dots adaptedto contact with the inking rolls in order to prevent these areas being filled with ink, which would result in dense smudges in the pic tures being printed. Such engraved plates can be produced with this present maclnne by placingia negative between the sensitized 'metal-plate and an unruled perfectly transp arent pressure. plate after the sensitized plate has been exposed to rays of light passing through a ruled screen, and altersuch second exposure and. developing a platewill be obtained which closely resembles a regular half-tone plate. For many purposes,

such a plate will give excellent proofs and will stereotype well. However, to those skilled in the art, such a plate lacks much in the middle tones that can only be brought out with a second screenexposure, which keeps the shadows well graded and open and still permits strong developing in the high-lights for the purpose of contrast where tones such as white skies are desired. In this second process employing two exposures, the dots are clear andgsh ar p while in the first they are usually clear in the high-lights and closed or smudged in the shadows. i

The present process must be distinguished from the usual pre-grained plate methods and single combined exposures of screenand negatives which give little more than a flat.

or smudged reproduction of the original,

and either over-expose the shadows or leave very weak high-light dots (if any dots) thereon. The principal advantages of the present invention are that the metal plate need not be grained before coating with a sensitized enamel; that the first screen fixes. the high-lights firmly while the second screen brings up the tones; that the larger openings in the second screen speed up the second exposure; that the regular camera negatives with their original tones permit the passage of light through the second screen to the metal plate, thus favoring tone values; and that the process greatlyreduces the time and expense of plate production. i The case 1 shown in the drawing may be of any desired construction, being shown with neither bottom nor top but provided with two partitions 2 (shown in dotted lines 10 and held down by a screw 11 whichpermit accurate vertical adjustment.

The guide 9 is mounted on a base 12 which is secured onto a bar 18 by means of screws 14. which pass through longitudinal slots -9, being pressed up bymeans of a spring j in this guide. The bar carries lugs 15 in which screws 16 are mounted and it is ap parent that upon loosening the screws i i that this base and the ointle '7 can be moved longitudinally of the side 3 of the case to which this particular bar 18 attached by means of screws 18. Any other desired type of hearing which permits of longitudinal and vertical adjustment may be en'iployed.

The screen 20 is similar in construction and in mounting to the screen 5 and the spacing of the lines of the screen is the same, but the lines are not so deep or heavy as those of the screen 5. its bearings are numbered 21. While I have de: F d the screen 5 as being on the leit and the screen 20 on the right, the positions of these screens may be interehangel if des red.

In order to provide a proper support for the screens I may secure a heavy plate of clear glass to the sides 3 and partitions 2 which is sulliciently strong to Withstand the pressures which may he appll-d thereto. Any other desired su pport may be employed.

Attached to the outer surface of the rear side 3 are two upright bars 2% which carry the bearings 25 for the shaft 26. These bearings are more clearly shown in Fig. 2 and embody a guide member 28 attached to the member 24 by means of screws 29. A block 30 constitutes the bearing for the shaft 26 and this block is pushed upward by the spring against the adjusting screw Mounted on the shaft is a flat plate holder to which attached a strip of metal by means of the screws 36, more clean ly shown in Fig. The inner edge of this strip is slightly beveled so to con. .i 'tute a good enga g surface for the beve edge of the sons .aed plate 87. This plate has its opposite edge engaged by nieansof a similar metal strip '88 which is attached direetly to a cross bar 25$) by means of screws 40 which pass through the spacing blociis all.

The holder formed with "i shag grooves in which these blocks are siidable, and the cross bar carries the small rods 44 which are slidaole in a statioi'iary bar and these rods tltl: carry the springs 41 6. The cross bar to is seen 'ed in position by means of the bolts t"? and wing nuts '8, *the bolts being slidable in the grooves in the holder 34. The springs e6 have sufficien't strength to so press the strip 558 against the sensitized plate 87 as to hold it sulliciently rigidly for all Pltltit-lCtl purposes. Because of this spring construction, the sensitized plates 37 can be quickly positioned on the holder and can be as readily removed, but when plates of a d'il'lerent size are to be printed, the wing nuts 48 are slacked and the cross bar moved to proper position for the new plates.

The case 1 is provided with pintles 50 which are rotatable in the uprights =51 carried by the base frame 52, and the light for the printing is preferably obtained from an are light 53-.

The mode of using this printing device is as follows: The sensitized plate 3'? is mounted on the holder as shown and the screen 5 with the line openings is folded down against the support 22, whereupon the sensitized plate is brought down against the screen and held in position in any desired manner, the spring hooks shown in liig. awhich engage the eyes 55 secured to the front 3 of the case being particularly adapted for this purpose, although any other de sired means may be employed. The use is then rotated until the plate 37 is at right in gies to the beam of lightfrom the are light which enters the bottom of the case and passes through the screen 5 to the sensitir/zed plate 37. After an exposure of about two minutes the case is turned to normal iositi'on, the spring hooks are released, the holder is swung up, the screen is swung back and the screen 20 swung into its position. 'l here upon, the photographic n ati've or drawing is placed upon the screen 20 end the sensitized plate is svv'ung down against it, the screws being turned back necessary to provide for this additional thiclrncs of the negative or o rwin-g. lVhen the negatives are in the form of colluloid films, no such adjustment is necessi The case is then again swung to ldl ll l tlilg position and light is permitted to pass through the screen 29 and the negative to the sensitized )late 37. When not in use, the screens are swung back into the case.

The sens ized plate is preferably so eoa m than an exposure of live mini-ites tlir {h the second screen sufficient to produce the desired results.

After developing, the positive print will seem to rest in a field of line dots and no details of the subject will be lost as picture is built-on the dots rather than be.. broken up by then: as is the case with l tone reproductions of line subjects. T ll 3514') line dots not only shade the subject but climinate the necessity of deep etching. Halftone and line plates can be compieiely peoduced by this process in twenty minutes, it being assumed that properly sensitized plates and negatives are on hand for the work. These plates are unmounted and are adapted for newspaper stereotypii'ig. It is not necessary for the engrin'ers to rout out the high-lights that have been broken down in the (levelopiinq or etchii'ig as is the case when the weak dots which occur on repro ductions of white surtl' aces are destroyed.

time of the first exposure and the second exposure can be timed to give either hard or soft outlines of the picture as desired. There are, therefore, four time limits, two for each exposure, which give the operator entire control of the tones and contacts. Heretotore, this had to be done by chemical manipulations which require considerable time and great skill.

While the screens can be ruled with great accuracy, the mounting may not always be so accurate, and the bearings shown in Fig. 3 are therefore desirable, for with them the screens can be adjusted relative to each other so that their lines will occupy absolutely the same positions when the screens are swung to operative position.

I clain z 1. In a device ofthe class described, the combination of a support, a pair of screens pivotally mounted thereon and adapted to be swung alternately to the'saine position, and a carrier for sensitized plates adapted to be moved to carry such plates into contact with said screens in succession, the lines on the two screens being similarly spaced and the screens and plate carrier being so mounted that the lines of both screens will affect the same portions of the sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitized plate.

2. In a device of the class described, the combination of a support, a pair of screens pivotally mounted thereon and adapted to be swung alternately to the same position, a carrier for sensitized plates adapted to be moved to carry such plates into contact with said screens in succession, and adjustable hearings for one of said screens the lines on the two screens being similarly spaced and the screens and plate carrier being so mounted that the lines of both screens will affect the same portions of the sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitized plate. 3. In a device of the class described, the combination of a support, a pair of screens pivotally mounted thereon and adapted to be swung alt rnately to the same position, a carrier tor sensitized plates adapted to be moved to carry such plates into contact with said screens in succession, and adjustable hearings tor one of said screens and the plate holder the lines on the two screens being similarly spaced andthe screens and plate carrier being so mounted that'the lines of both screens will affect the same portions of the sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitizedplate' 4:, In a device of the class described, the combination ofa support, a pair of screens pivotally mounted thereon and adapted to be swung alternately to the same position, a carrier for sensitized plates adapted to be moved to carry such plates into contact with said screens in succession,v pivots for said support, and a source of light positioned to project rays of light through thescreens as the support is turned on its pivots the lines on the two screens being similarly spaced and the screens and plate carrier being so mounted that the lines of both screens will aiiect'the same portions of the sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitized plate.

5. In a deviceoi the class described, the combination of a support embodying a glass plate, a pair of screens pivotally mounted thereon and adapted to be swung alternately into contact with said glass plate, and a car rier for sensitized plates pivoted on the support and adapted to be swung to carry such plates into contact with said screens in succession, the lines on the two screens being similarly spaced and the screens and plate rarrier being so mounted that the lines of both screens will aiifectthe same portions of the sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitized plate.

6. In a device of the class described, the combination of a support, apair of screens pivotally mounted thereon and adapted to be swung alternately and independently of each other to the same position, a carrier for sensitized plates adapted to be moved to carry such plates into contact with said screens in succession, the spaces between the lines of one screen being smaller than the spaces between the lines of the other the lines on the two screens being similarly spaced and the screens and plate carrier being so mounted that the lines of both screen will affect the same portions ofthe sensitized plates and a source of light adapted to produce rays which pass unobstructed by lenses through said screens to the sensitized plate.

7; In a device of the class described, the combination 01' a support, a pair of screens pivotally mounted thereon and adapted to be swung alternately to the same position, and a carrier forsensitized plates adapted to be moved to carry such plates into con tact with said screens in succession, the spaces between the lines of the first screen employed being smaller than those between the lines of the second screen the lines on the IOU two screens being similarly spaced and the I screens and plate carrier being so mounted that the hues of both screens will aiiect the same portions of the sensitizedplates and a sourcerof light adapted to produce rays which pass unobstructed bv lenses through said screens to the sensitized plate.

8. In a device of the class described, the apart but the lines :of one screen being Wider combination of a support, a pair of transthan those 0% the other, and a source of light parent screens mounted thereon, a carrier adapted to produce rays which pass unobfor sensitized metal plates adapted to be structed and unchanged through said screens 5 moved to carry such plates into Contact to the sensitized metal plate.

with such screens in succession, the lines of said screens being spaced the same distance ROY K. CARSON. 

